Determination of ciprofloxacin and enoxacin in human serum samples by micellar liquid chromatography

A simple and rapid micellar liquid chromatographic (MLC) method with UV detection for the determination of ciprofloxacin and enoxacin has been developed. The separation was performed in 75 mM SDS—10 mM phosphate buffer—18 mM TBABr/3% (v/v) 1-propanol at pH 3.0. Analyses were realised using a Lichrospher 100RP18 column (125 mm × 4 mm i.d., 5 (mu)m particle) and the operating conditions were: 0.9 ml min^-1 flow rate, 25 (mu)l volume injection and detection at 281 nm. Tosufloxacin was used as an internal standard. The linear concentration range of application was 0.10–5.00 (mu)g ml^-1 for both compounds, with a detection limit of 0.024 (mu)g ml^-1 for ciprofloxacin and 0.025 (mu)g ml^-1 for enoxacin, respectively. The analysis yielded good repeatability (RSD between 2.98 and 4.71%). The method shows recoveries for the two fluoroquinolones ranging from 93.0 to 105.4%. The proposed method was applied to human serum samples of subjects administered with these antibacterials.